Emergency release switch



Jan. 7, 1964 R. D. BUSH I 3,117,205

EMERGENCY RELEASE SWITCH Filed July 31, 1961 United States Patent 3,117,206 ENIERGEN CY RELEASE SWITCH Rex Devon Bush, Columbus, Ohio, assignor to Cutler- Hammer, Inc, Milwaukee, Wis., a corporation of Delaware Filed .luly 31, 1961, Ser. No. 127,976 4 Claims. (Cl. 200-157) This invention relates to emergency release electric switches.

The invention pertains to switches of the emergency release type described in the Cranmore Patent No. 2,928,- 921 and Park et a1. Patent No. 2,947,840 and is an improvernent.

A primary object of the present invention is to provide a switch of the aforementioned type which is greatly simplified in respect of the number of parts and in the operation thereof to provide normal and emergency release operation.

Other objects and advantages will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment which will now be described in detail, it being understood that the embodiment illustrated is susceptible of modification in respect of details without departing from the scope of the appended claims.

In the drawings,

FIGURE 1 is a side elevational view of a trigger type switch incorporating the invention;

FIG. 2 is a front end view;

FIG. 3 is a fragmentary sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a sectional view taken along the line 44 of FIG. 3;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 3;

FIG. 6 is an isometric view of a part shown in FIGS. 3 and 4;

FIG. 7 is a fragmentary sectional view of the switch showing the switch in another normal operating condition; and

FIG. 8 is a view like FIG. 7, but shows the switch in its emergency release operating condition.

Referring to the drawing, it shows a trigger lever switch such as used in portable electric tools or the like. More particularly, the switch comprises a molded insulating base 19, a trigger operator 12, and a combined cover and assembly securing frame 14. Base 10 has an interior cavity 16 to which is mounted a stationary contact 18 that is secured to a terminal member 20 seating in a slot extending from the lower outer surface to the lower inner surface of the base. A part of terminal 20 overlies and has an opening alined with a threaded insert 22. A wire clamping screw 24 penetrates the opening and takes into the recess 22.

A resilient movable contactor 26 which is of a preferred form best shown in FIG. 6 is U-shaped adjacent one end and the short leg 26a thereof seats with a complementally formed slot connecting the cavity 16 with the lower outer surface of base 10. The portion 26a adjacent its free end is provided with an opening alined with a threaded insert 28 in base 10, and a wire retaining screw 29 penetrates the same and takes into the insert 30. Contactor 26 has a long relatively narrow rectangular portion 26b which substantially extends the length of cavity 16 and adjacent its free end has a contact 32 aflixed thereto in overlying relation to the stationary contact 18. Contactor 26 is inherently biased so that in relaxed condition its contact 32 is separated from the contact 18 as shown in FIG. 3 and the upper surface of the adjacent free end of the portion 26b abuts against the overhanging ledge 10a of the base 10. To the right of the longitudinal medial point of the portion "ice 26b the latter is provided with integral laterally extending tab or wing portions 260.

Trigger lever 12 is provided with an overhanging finger grip portion 12a which is integrally attached to one end of a generally rectangular cross section slide block portion 12b. The upper U-shaped channel portion 14a of frame 14 provides a guideway in cooperation with the upper surface 10b of base 10 in which the portion 12b is slidable. The frame has depending ears 14b at each corner and the same are turned in against lower shoulders in recesses formed adjacent each of the lower corners of base 10 to'secure the frame to the base.

A- coiled compression spring 28 seats at one end in a cylindrical-recess 30 formed in one end of portion 12b of trigger lever 12 and atits-opposite end against a raised boss 34a ona spring plate 34 that seats against the in ner side of the closed'end 14c of the portion 14a of frame 14. Spring 28 biases trigger 12 to -a left-hand extreme position, as viewed in FIGS. 1 and 3, defined by engagement of an' operating member 36 with an overhanging ledge 10d of base 10. Plate 34 has spring tabs 34b that are struck out and bent toward the lever portion 12 for a purpose hereinafter to be described. The portion 12b is provided with another recess 38 in which is positioned a coil compression spring 40 and steel ball 42 to provide a position defining detent mechanism in cooperation with the spaced apart openings 44 and 46 formed in the top of the portion 14a of the frame.

Operating member 36 is formed of two identical pieces 36a and 36b molded in place in the portion 12b in opposing relation and provides a sloping channel section 360 which has inwardly turned opposing flanges 36d overlying the open side of the channel. The opening between the opposing ends of' the flanges 36d is slightly greater than the width of the major portion 26b but less than its width at tabs 260.

As will be seen with trigger 12 in the position depicted in FIG. 3, operating member 36 will be disengaged from movable contactor 26 and the latter assumes its circuit interrupting position depicted in FIG. 3. When trigger 12 is moved to the right the lower sides of the flanges 36d will engage with the upper surfaces of the tabs 260 of contactor 32 and upon continued right-hand movement will press contactor 26 downwardly. When detent ball 42 engages with opening 46 the contact 32 will be in circuit completing engagement with stationary contact 18. If trigger 12 is then released the energy stored in the compressed spring 28 will return trigger 12 and drive member 36 to the left-hand extreme position depicted in FIG. 3. Consequently, member 36 disengages from the tabs 26c to permit member 26 under its inherent bias to disengage its contact 32 from stationary contact 18 for circuit interruption.

Now let it be assumed that trigger 12, operating member 36 and contactor 26 are in the normal circuit com pleting position depicted in FIG. 7. If trigger 12 is squeezed harder by the operator, as might naturally occur if a drill or cutter in the tool in which the switch is mounted becomes seized or bound, it will move farther to the right against the resistance afforded by the spring tabs 34a. In so moving the flanges 36d of member 36 would move to the right off of the tabs 26c which permits contactor 26 to spring back to contact disengaged position shown in FIG. 8. As contactor 26 is then disposed within the space between the walls of the channel 360, member 36 in moving to the left when trigger 12 is released, will prevent contactor 36 from engaging with stationary contact 18 until member 36 has returned to its left-hand extreme position depicted in FIG. 3.

If desired, operating member 36 could comprise a single one of the pieces 36:: or 36b in which case only one tab 260 need be provided on contactor 26. However,

the use of the two pieces 36a and 36b for member 36 insures a more even distribution of operating forces across the width of the contactor 26 thus insuring better alinement and engagement of the latters contact 32 with stationary contact 18. While member 36 could be'made of a single piece the use of the two pieces 36a and 36b makes for simpler and less costly manufacture.

I claim:

1. In an electric switch, in combination, a housing, a stationary contact mounted in said housing, a resilient movable contactor in said housing normally biased out of engagement with said stationary contact, and operating means for said movable contactor including a member normally biased to an extreme position out of engagement with said contactor, said contactor and said member having means which upon movement of said member a given distance from said extreme position efiect engagement therebetween to press said contactor into engagement with said stationary contact, said means upon further movement of said member in the same direction aifording disengagement of said member from said contactor to permit said contactor to disengage from said stationary contact, and said means upon said contactor moving back from the last mentioned contactor disengaging position to the first mentioned extreme position preventing engagement of said contactor with said stationary contact.

2. The combination according to claim 1, wherein said contactor has a laterally extending tab and said member is provided with a portion having spaced but interconnected parallel arms, one of which engages said tab when said member is moved, said given distance from its extreme position to press said contactor into engagement with said stationary contact, said member when moving from said contactor disengaging position back to said extreme position having its parallel arms disposed about said contactor.

3. The combination according to claim 1, wherein said contactor has oppositely disposed laterally extending tabs and said member is provided with a channel-shaped portion with flanges extending laterally toward each other at the open side thereof, said member when moved said given distance engaging its flanges with said tabs of said contactor to press the contactor into engagement with said stationary contacts, said member upon movement from said contactor disengaging position to said extreme position having its channel-shaped portion disposed about said contactor.

4. In an electric switch, in combination, a molded insulating base having a cavity formed therein, a stationary contact mounted in said cavity, a resilient contactor mounted in said cavity and inherently biased to disengaged relation with respect to said stationary contact, said contactor having laterally extending tabs along a portion thereof, a block rectilinearly slidable on said base over said cavity, a frame secured to said base and surrounding and providing guideways for the aforementioned movement of said block, an operating member secured to said block in operative relation to said contactor and having a channel-shaped portion with coplanar inwardly turned end flanges, a spring interposed between Said frame and said block biasing the latter to a given extreme position wherein said operating member is disengaged from said contactor, said block being movable against the bias of said spring a certain distance to engage the References Cited in the file of this patent UNITED STATES PATENTS 2,616,009 Roeser Oct. 28, 1952 2,928,921 Cranmore Mar. 15, 1960 2,947,840 Park et a1. Aug. 2, 1960 

1. IN AN ELECTRIC SWITCH, IN COMBINATION, A HOUSING, A STATIONARY CONTACT MOUNTED IN SAID HOUSING, A RESILIENT MOVABLE CONTACTOR IN SAID HOUSING NORMALLY BIASED OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACT, AND OPERATING MEANS FOR SAID MOVABLE CONTACTOR INCLUDING A MEMBER NORMALLY BIASED TO AN EXTREME POSITION OUT OF ENGAGEMENT WITH SAID CONTACTOR, SAID CONTACTOR AND SAID MEMBER HAVING MEANS WHICH UPON MOVEMENT OF SAID MEMBER A GIVEN DISTANCE FROM SAID EXTREME POSITION EFFECT ENGAGEMENT THEREBETWEEN TO PRESS SAID CONTACTOR INTO ENGAGEMENT WITH SAID STATIONARY CONTACT, SAID MEANS UPON FURTHER MOVEMENT OF SAID MEMBER IN THE SAME DIRECTION AFFORDING DISENGAGEMENT OF SAID MEMBER FROM SAID CONTACTOR TO PERMIT SAID CONTACTOR TO DISENGAGE FROM SAID STATIONARY CONTACT, AND SAID MEANS UPON SAID CONTACTOR MOVING BACK FROM THE LAST MENTIONED CONTACTOR DISENGAGING POSITION TO THE FIRST MENTIONED EXTREME POSITION PREVENTING ENGAGEMENT OF SAID CONTACTOR WITH SAID STATIONARY CONTACT. 